Measurement of the probability for gluon splitting into b bbar in Z0 decays

TL;DR

This paper reports a measurement of the rate at which gluons split into bottom quark pairs in Z0 decays, using advanced vertex detection techniques to identify secondary bottom production in four-jet events.

Contribution

It provides a novel measurement of gluon splitting into bottom quarks in Z0 decays using a topological vertex-mass technique with high B-tagging efficiency.

Findings

Measured g_bb rate as (3.07+-0.71(stat)+-0.66(syst)) * 10^-3

Demonstrated effectiveness of CCD vertex detector for low-energy B hadron detection

Identified g -> b bbar events in hadronic Z0 decays

Abstract

We present a preliminary measurement of the rate of gluon splitting into bottom quarks, g -> b bbar, in hadronic Z0 decays collected by SLD between 1996 and 1998. The analysis was performed by looking for secondary bottom production in 4-jet events of any primary flavour. 4-jet events were identified, and a topological vertex-mass technique was applied to each jet in order to identify b or bbar jets. The upgraded CCD based vertex detector gives very high B-tagging efficiency, especially for B hadrons of the low energies typical of this process. The two most nearly collinear b/bbar jets were tagged as originating from g -> b bbar. We measured the rate of secondary b/bbar production per hadronic event, g_bb, to be (3.07+-0.71(stat.)+-0.66(syst.)) * 10**-3.